A polycarbonate resin is a polycarbonate ester obtained from the reaction of bisphenol A (2,2-bis-(4-hydroxyphenyl) propane) with phosgene or carbonate ester. In comparison with other resins, polycarbonate resins have superior mechanical strength, impact resistance, heat resistance, and transparency. Thus, polycarbonate resins have been used as an engineering plastic in, for example, electrical devices, automobile components, and construction material.
A filler may be mixed with a polycarbonate resin to further improve the mechanical strength or heat resistance of the polycarbonate resin. Normally, glass fillers having the form of flakes, fibers, particles, beads, and the like are used to reinforce a thermoplastic plastic or the like. Preferable glass compositions include an alkali-free silicate glass such as an E glass, an alkali silicate glass such as a C glass, and a normal sheet glass.
However, when using these glass compositions as the glass filler to be mixed with polycarbonate resin, the performance of the polycarbonate resin may be adversely affected. More specifically, when using a C glass composition or a sheet glass composition, the alkali ions in these compositions may cause hydrolytic reaction that decreases the molecular weight of the polycarbonate resin. This reduces the mechanical strength of a product molded from the polycarbonate resin. Further, when using an E glass composition, the difference in refractive index between the polycarbonate resin and the glass filler scatters light at the interface of the polycarbonate resin and the glass filler. As a result, the transparency of the polycarbonate resin may be degraded.
Nowadays, glass fillers suitable for mixing with a polycarbonate resin have become practical.
Japanese Examined Patent Publication No. 62-1338 discloses a glass fiber composition consisting of glass having a refractive index that is close to that of a polycarbonate resin so that the transparency of the polycarbonate resin is not degraded.
Japanese Laid-Open Patent Publication No. 5-155638 discloses a glass composition that has a refractive index of 1.570 to 1.600 and is only subtly colored. Moreover, decrease of the molecular weight of a resin in the glass composition is prevented.
WO2005/110695 discloses glass fibers that can maintain the transparency of a molded product after being reinforced with fibers and increase the refractive index to a level that is substantially the same as the refractive index of polycarbonate resin. A glass fiber-reinforced polycarbonate resin molded product using the same is also disclosed.
Japanese Laid-Open Patent Publication No. 2006-22235 discloses a polycarbonate resin composition having superior transparency and mechanical strength and including a glass filler having a refractive index that is substantially the same as that of polycarbonate resin.
Japanese Laid-Open Patent Publication No. 2006-22236 discloses a polycarbonate resin composition having superior transparency and mechanical strength and including a glass filler having a refractive index that is substantially the same as that of polycarbonate resin.
Japanese Laid-Open Patent Publication No. 2007-153729 discloses a glass filler for a polycarbonate resin which filler can maintain the transparency of a molded product after reinforcing the glass filler and increase the refractive index to a level that is substantially the same as the refractive index of polycarbonate resin. A polycarbonate resin composition using the glass filler is also disclosed.
Japanese Laid-Open Patent Publication No. 61-14152 discloses glass fibers having properties that are suitable for use as a reinforcing material for electrical applications. It discloses that a typical glass fiber having a typical glass composition has a refractive index of 1.57.
Japanese Laid-Open Patent Publication No. 2005-97080 discloses glass flakes having sufficient heat resistance and satisfactory moldability. The glass flakes are mixed in resin molded products, paints, makeup materials, and ink.    Patent Document 1: Japanese Examined Patent Publication No. 62-1338    Patent Document 2: Japanese Laid-Open Patent Publication No. 5-155638    Patent Document 3: WO2005/110695    Patent Document 4: Japanese Laid-Open Patent Publication No. 2006-22235    Patent Document 5: Japanese Laid-Open Patent Publication No. 2006-22236    Patent Document 6: Japanese Laid-Open Patent Publication No. 2007-153729    Patent Document 7: Japanese Laid-Open Patent Publication No. 61-14152    Patent Document 8: Japanese Laid-Open Patent Publication No. 2005-97080